code: def add_children(G, parent, level, n=2):
      """Add children recursively to a binary tree."""
      if level == 0:
          return
      for i in range(n):
          child = parent + str(i)
          G.add_node(child)
          G.add_edge(parent, child)
          add_children(G, child, level - 1, n)
  
file_path: ipyparallel/examples/dagdeps.py
imports: from random import randint
  import networkx
  import ipyparallel
label_desc: Use image node_id 3 for calling a global function with example usage: add_children(G, parent, level, n) without return types